android - SQLite - 删除命令中没有这样的列

Question

public void addFavourite(User user,Winkel winkel){
    ContentValues values = new ContentValues();
    values.put(COLUMN_NAME,winkel.getNaam());
    values.put(COLUMN_POSTCODE, winkel.getPostcode());
    values.put(COLUMN_DEELGEMEENTE, winkel.getDeelGemeente());
    values.put(COLUMN_GEMEENTE, winkel.getGemeente());
    values.put(COLUMN_ADRES, winkel.getAdres());
    Log.d("lol",user.getUserName()); // Log is succesfull
    values.put(COLUMN_USERNAME, user.getUserName());
    SQLiteDatabase db = this.getWritableDatabase();
    db.insert(TABLE_FAVOURITES, null, values);
    db.close();

}

public void deleteFavourite(User user,Winkel winkel){

    String selectQuery = "DELETE FROM " + TABLE_FAVOURITES + " WHERE " + COLUMN_USERNAME+"=" + user.getUserName() + " AND " + COLUMN_NAME + "=" + winkel.getNaam();
    SQLiteDatabase db = this.getWritableDatabase();
    db.execSQL(selectQuery);
    db.close();
}


    String CREATE_FAVOURITES_TABLE = "CREATE TABLE IF NOT EXISTS " +
            TABLE_FAVOURITES + "("
            + COLUMN_ID2 + " INTEGER PRIMARY KEY,"
            + COLUMN_NAME + " TEXT,"
            + COLUMN_POSTCODE + " INTEGER,"
            + COLUMN_DEELGEMEENTE + " TEXT,"
            + COLUMN_GEMEENTE + " TEXT,"
            + COLUMN_ADRES + " TEXT,"
            + COLUMN_USERNAME + " TEXT, "
            + "FOREIGN KEY(" + COLUMN_USERNAME+ ") REFERENCES "
            + TABLE_USERS + "(username) " + ")";
    db.execSQL(CREATE_FAVOURITES_TABLE);

尝试删除收藏夹时的 SQL 异常:

android.database.sqlite.SQLiteException: no such column: Gebruikersnaam (code 1): , while compiling: DELETE FROM favorieten WHERE username=Gebruikersnaam AND naam=EUROCITY

注意:所以我假设在添加收藏夹时出现问题，用户名实际上没有添加到表中，或者我的创建表语句中有问题，或者我的 deletequery 中有问题。我不知道是什么。为什么这不起作用？

Answer 1

您需要用单引号将您的字符串括起来。
即:WHERE username='Gebruikersnaam' AND naam='EUROCITY'

绑定(bind)参数会更好。
如果字符串包含一个或多个撇号 ("'" => "''")，它们还会将单引号加倍。
因此您不必手动更换它们。

在你的情况下，它是这样的:

// Put your parameters in this array (no matter if they are numeric types
// because the SQL statement is a string anyway),
// in the exact order of appearance in your query or SQL command
String[] strParams = new String[]{user.getUserName(), winkel.getNaam()};
// Your modified SQL command with the parameter placeholders (?)
String selectQuery = "DELETE FROM " + TABLE_FAVOURITES + 
    " WHERE " + COLUMN_USERNAME + " = ? AND " + COLUMN_NAME + " = ?";
SQLiteDatabase db = this.getWritableDatabase();
// Use this execSQL() syntax
db.execSQL(selectQuery, strParams);
db.close();